Bough decides to tail the man across London, following him from a train station onto a rail replacement bus. During the ride, Bough realizes he is in trouble; he appears to suffer a panic attack and frantically types a single word into his phone: . When the bus reaches its final stop, the driver finds Bough dead in his seat, apparently of a heart attack. Jackson Lamb Investigates
The story begins with , a retired field agent who now runs a sex shop in Soho. During a downpour, he spots a man outside his shop who triggers a traumatic memory of being kidnapped and tortured decades ago.
Slough House's obnoxious but brilliant leader, (Gary Oldman), isn't convinced by the "natural causes" explanation. He visits the bus depot, posing as a grieving relative to swipe Bough’s hidden phone. Upon seeing the word "Cicada," Lamb goes on high alert.